Efficient separation of Zn(Ⅱ) from Cd(Ⅱ) in sulfate solution by mechanochemically activated serpentine

Our plain-English summary of Efficient separation of Zn(Ⅱ) from Cd(Ⅱ) in sulfate solution by mechanochemically activated serpentine, by Z. Li, P. Huang, H. Hu, et al (Chemosphere, 2020).

The study

• Authors: Z. Li, P. Huang, H. Hu, Q. Zhang, M. Chen
• Journal: Chemosphere
• Published: 2020;258:127275
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Clay minerals are widely used to treat sewage containing heavy metals such as zinc and cadmium. In this study, the chemical reactivity of natural serpentine was signally improved through mechanochemical activation, achieving the efficient separation of Zn(Ⅱ) and Cd(Ⅱ) ions in a mixed solution. The activated serpentine would release a large amount of Mg2+ and OH- and thereby selectively precipitate Zn(Ⅱ) ions as an uncommon metamorphic zinc mineral, bechererite, in the presence of SO42-. By adjusting the parameters including grinding intensity, reaction temperature, serpentine dosage and salt species, the optimum conditions were determined and a 92% separation rate of Zn(Ⅱ) and Cd(Ⅱ) ions was achieved. The mechanochemical activation of natural clay minerals expresses a great potential for purification of heavy metal contaminated sewage, as well as the simultaneous separation and recovery of multi-metal secondary resources.

Copyright © 2020 Elsevier Ltd. All rights reserved.

In plain English

This short laboratory chemistry study tested whether ground serpentine mineral could separate dissolved zinc from dissolved cadmium in water. It did not study people, health or asbestos, and the article never mentions asbestos, chrysotile or fibers. The authors bought natural serpentine from Jinchuan Group Ltd., China, ground it dry in a mill for 60 minutes at different speeds, and added it to a solution holding 1000 mg/L each of zinc and cadmium. Unground serpentine did little. With serpentine ground at 600 rpm, used at 2.5 g/L and at 90 degrees C, 7.41% of the zinc stayed in solution while 92.55% of the cadmium remained. Zinc came out mainly as a rare mineral, bechererite, and this needed sulfate in the solution. The authors concluded that the zinc precipitation rate was over 92% under the best conditions, and that activated clay minerals have potential for cleaning metal-polluted sewage and recovering metals. They said the role of sulfate needs more research, and that recovering the zinc and cadmium was their next step.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory chemistry experiment (short communication); no human or animal subjects
• Who was studied: No people were studied. The material was a natural serpentine mineral sample bought from Jinchuan Group Ltd., China, tested in prepared zinc and cadmium solutions.
• Exposure: No human exposure was studied. Serpentine was ground dry in a planetary mill for 60 minutes at varying speeds, then added to 40 mL of mixed zinc and cadmium solution (1000 mg/L each) and shaken for 3 hours at set temperatures.
• Main results:
  • Raw (unground) serpentine precipitated little zinc or cadmium, even when heated up to 90 degrees C.
  • With activated serpentine, the share of zinc left in solution fell from 82.39% at 50 degrees C to 7.41% at 90 degrees C, while cadmium stayed above 92%.
  • Serpentine ground at 600 rpm left 7.41% of zinc in solution, while 92.55% of cadmium remained.
  • A dose of 2.5 g/L worked best. At 3.75 g/L, zinc left in solution was only 0.47%, but cadmium left in solution also dropped to 75.41%, so separation was worse.
  • In chloride or nitrate solutions, more than 90% of both zinc and cadmium remained. Adding sodium sulfate brought the zinc remaining below 10%.
  • The pH produced by raw serpentine was 6.26, and by activated serpentine 10.8. The activated sample was amorphous (its crystal structure was destroyed).
  • The main solid formed after separation was the zinc mineral bechererite.
• The authors' conclusion: The authors concluded that a zinc selective precipitation rate of over 92% was achieved under optimum conditions, and that mechanochemically activated natural clay minerals have potential for purifying heavy-metal-contaminated sewage and recovering metals.
• Limitations the authors state:
  • The authors said the role of sulfate in the zinc reaction needs more detailed research.
  • Actual recovery of zinc from the solid and cadmium from the solution was not done in this study; the authors described it as the next step.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Serpentine Group.

Related studies

• Screening and Optimization of Conditions for the Adsorption of Cd2+ in Serpentine by Using Response Surface Methodology — X. Zhang, L. Du, et al. (2022)
• Reaction mechanism for the aqueous-phase mineral carbonation of heat-activated serpentine at low temperatures and pressures in flue gas conditions — L.C. Pasquier, G. Mercier, et al. (2014)
• A case-referent study of cancer mortality among sulfate mill workers in Sweden — E. Andersson, S. Hagberg, et al. (2001)
• The biological effect of asbestos exposure is dependent on changes in iron homeostasis — A.J. Ghio, J.M. Soukup, et al. (2016)
• Efficient and versatile fibrous adsorbent based on magnetic amphiphilic composites of chrysotile/carbon nanostructures for the removal of ethynilestradiol — A.P. Teixeira, A.D. Purceno, et al. (2013)
• Influence of metal ions on flavonoid protection against asbestos-induced cell injury — V.A. Kostyuk, A.I. Potapovich, et al. (2001)

Browse more research in Chemosphere, or return to medical research.